717
FXUS61 KBTV 110842
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
442 AM EDT Sun Apr 11 2021

.SYNOPSIS...
A weak occluded front will bring increased cloud cover and chances
for rain to portions of northern New York and southern Vermont this
afternoon. However, most locations are expected to remain dry with
cooler temperatures as a backdoor cold front approaches from the
northeast. Scattered showers will remain possible through Tuesday
but it appears we are in for another quiet week of weather with high
pressure once again building back across the region. Temperatures
won`t be quite as warm this week as they were last week with high
temperatures each afternoon in the upper 50s to lower 60s.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 358 AM EDT Sunday...A couple of weak fronts will make a run at
each other from opposite sides of the forecast area today and
Monday, with the overall result being the chance for scattered
showers over portions of our area. The first front will be a
backdoor cold front, which currently lies poised just to our north
and east. Cooler maritime air will spread into eastern VT as this
front makes its way westward. Meanwhile, an occluded front
positioned to our southwest will push toward our region, spreading
showers northeastward as it does so. Unfortunately, with the drier
air behind the cold front and ridging aloft will work against the
occluded front, limiting the forward progress of the precipitation.
Showers will make it into northern New York and portions of southern
Vermont, but expect most areas will be dry, particularly east of a
line from Ellenburg Depot to Waitsfield to Stafford. West of this
line, scattered showers will come and go this afternoon through
Monday, with total rainfall amounts generally a few hundredths to
perhaps up to a third of an inch in far western St Lawrence County.
Note that some of the hi-res CAM guidance is indicating some pop up
convection ahead of the occluded front in portions of far northern
NY/Champlain Valley. There will be a bit of elevated instability,
but overall convective threat is minimal so have left out any
mention of thunder. Temperatures are a bit tricky given the two
boundaries that will be at play. Areas from the Champlain Valley
westward will top out in the upper 60s to lower 70s. East of the
Greens, the backdoor front will keep temperatures in the lower to
mid 60s. It will be even cooler tomorrow, generally in the mid 50s
to mid 60s. This is near normal for mid May, but it will feel cool
compared to the recent warmth we`ve had. Lows tonight will be in the
upper 30s to upper 40s, coolest in the sheltered valleys in the
higher terrain.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 358 AM EDT Sunday...Retrograding pattern with a stable air mass
advancing in from the east remains the expectation for Monday night,
with any lingering rain showers over western portions of the
forecast area being shunted to the west as the upper level energy
tracks across the Mid- Atlantic states. The east or northeast low-
level flow will support development of a thick overcast over eastern
Vermont where surface winds will be negligible. During the daytime,
neither surface heating nor dry air aloft will be sufficient to mix
out the clouds, which will be trapped under a relatively high -
several thousand foot - inversion. Elsewhere, skies generally should
be partly to mostly cloudy, although where the easterly mid-level
flow results in downsloping, such as in the eastern Champlain
Valley, the clouds should dissipate more quickly and temperatures
recover a little better. Highs will end up roughly 5 degrees above
normal in many areas from the Green Mountains west, with near or
possibly below normal temperatures east of the Greens. While
measurable rain not expected, very light showers are possible over
eastern Vermont during the day as a subtle upper-level wave moves
southwestward, causing enough vertical motion in the clouds to
promote precipitation.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 442 AM EDT Sunday...Another occluded front will advance towards
the area Tuesday night, and yet again have trouble moving eastward
through the whole region. Currently good agreement from model
guidance that again only northern New York gets precipitation from
this boundary before it fizzles out. However, during the day on
Wednesday, it appears the occluded low pressure system will be large
enough and track far enough north to support surface convergence in
much of the North Country, enough so to result in scattered showers.
The broad, disorganized system will not have much in the way of
thermal gradients or strong wind fields, so precipitation will be
light. Temperatures should be near normal or a few degrees above
normal, reaching into the mid and upper 50s in most areas.

Things may get more interesting on Thursday, as the latest guidance
strongly suggests that the upper-level troughing moving eastward
Wednesday night will phase with southern stream energy, with rapid
cyclogenesis taking place somewhere east of the central
Appalachians. The latest global deterministic models have this low
pressure area somewhere between the DelMarVa and Cape Hatteras early
on Thursday, with the GFS relatively far south and east. As a
result, the circulation stays offshore and well south of our area,
with dry, mild northeast winds across the North Country. However,
both the Canadian and European solutions are far enough north and
west to bring steady rainfall to at least portions of the forecast
area. However, very little support for a large rain event in excess
of 1" exists at this time. In fact, even with a relatively favorable
track near Cape Cod in the Canadian model, the ensemble system
suggests even rainfall exceeding 0.1" is relatively unlikely. The
ECMWF ensemble is a little more encouraging for significant
rainfall, with about a 50% chance of rainfall exceeding 0.5" across
much of Vermont and northeastern New York. Since a cloudy and wet
period from Thursday into early Friday would mark a dramatic shift
from the previous forecast, the current forecast does not yet call
for this rainfall. But if the next cycle has more support for an
east coast low pressure system sufficiently north and west, expect
to see precipitation chances come up a bit.

The remainder of the forecast period really will be determined by
what happens with the potential storm on Thursday. The weekend looks
potentially unsettled with additional shower chances if the low
pressure system lifts northward along the coast, which would help
establish a synoptic pattern featuring the mean trough sitting over
the northeastern US. Areas of low pressure would then dumbbell
around the trough, with better chances of showers along with
cooler conditions will probably holding off until Sunday.
However, if the storm on Thursday goes harmlessly out to see, we
will not only miss out on rain then but we will likely remain
in light flow pattern with weak surface high pressure keeping us
high and dry, with temperatures trending a bit warmer. Stay
tuned.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
Through 06Z Monday...Mainly VFR with high clouds at or above
10 kft agl for the most part. Tricky forecast for wind
direction, with several competing influences for the next 12
hours. Towards 12Z, a transition towards east to southeast winds
will be likely, and after 15Z wind speeds increase to 7 to 12
knots, gusting at KRUT up to 20 knots at times. Low level
stratus begins to move into eastern and southern sites on east
flow after 12z, bring ceilings down to 1500-3000 ft 12z-16z. Beyond
18Z, frontal system approaches from the southwest, but will be
slow to move into our region with scattered shower activity and
ceilings 3000-6000 ft. VCSH mentioned at KMSS, KSLK, and KRUT
for this. The front continues to impact the region beyond 06Z
Monday.

Outlook...

Monday: VFR. Slight chance SHRA.
Monday Night: VFR. Slight chance SHRA.
Tuesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.
Wednesday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Thursday: VFR. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Hastings
SHORT TERM...Kutikoff
LONG TERM...Kutikoff
AVIATION...Hastings